The degradation mechanism of an AlGaN/GaN high electron mobility transistor under step-stress

Abstract

Step-stress experiments are performed in this paper to investigate the degradation mechanism of an AlGaN/GaN high electron mobility transistor (HEMT). It is found that the stress current shows a recoverable decrease during each voltage step and there is a critical voltage beyond which the stress current starts to increase sharply in our experiments. We postulate that defects may be randomly induced within the AlGaN barrier by the high electric field during each voltage step. But once the critical voltage is reached, the trap concentration will increase sharply due to the inverse piezoelectric effect. A leakage path may be introduced by excessive defect, and this may result in the permanent degradation of the AlGaN/GaN HEMT.